Like others, I was confused by this:
One use case of pinned topics are long-running devlogs / diaries. Having the topic unpin itself is rather inconvenient as it will eventually get lost.
Can automatic unpinning of topics be disabled, preferably on a per user basis?
There is a site setting to disable it globally, I kind of wish we allowed you to pick per-pin
Yes, I just found the related discussion:
https://meta.discourse.org/t/allow-welcome-pinned-topic-to-be-unpinned-for-regular-users/9795/
I suppose it’ll be part of the next release?
Thanks guys, awesome support as always.
The disable flag is in latest, per user or per pin option was discussed but is not planned
I have unpinned quite a few topics after reading them.
The easiest way to find them again that I’ve found is to visit while not logged in.
A bit inconvenient and not the easiest thing to do or teach to others, but it works.
We discussed this and based on the feedback we received, we added a new user preference 
https://github.com/discourse/discourse/commit/92ba6125c4a349b3ffefdfead3f1086d1ba77488
Gonna upgrade my setup now thanks 
Just updated, thanks!
Not sure to understand why there are two settings (Automatically unpin and Automatically unpin by default) since there are no per-topic unpin setting… Yet?
The “automatically_unpin_topics” setting is used to globally enable/disable the feature while the “default_topics_automatic_unpin” setting is used to set the default user preference.
You might want to have the feature enabled globally but defaulted to off for your new users.
Ah, so this is a per-user setting? I can’t find it in my user preferences.
Exactly, it’s now a per-user setting.
It’s near the bottom
Not here…
Are you running the latest version of Discourse? I added this new setting less than an hour ago 
I just updated, and I do have the other (site) settings regarding automatic unpinning… Did you do multiple commits?
The “automatically_unpin_topic” setting was added about a couple of days ago.
Oh, right. Will get the per-user setting in the next update then. Thanks!
Do I understand things correctly that when a pinned topic only has a single post, the topic gets unpinned as soon as that post is displayed for the user? Or only after it has been displayed for a certain amount of time?
I think it would be good if the automatic unpinning would only be triggered if a topic has been viewed for a certain amount of time. Reason: if you pin a topic, the idea is to make sure that people read it. If it is only one post (perhaps because it is a closed announcement) and people only briefly look at it, you might want to keep it pinned for them until they take a closer look.
Topic is only unpinned for a user once it reaches the end of that topic. If it’s a one-post topic, then I guess it’s the same as viewing that post.
Okay, fine. Then what do you think about adding a timer before it is unpinned? The timer will be irrelevant for longer topics but would be useful for one-post topics.